The code of conduct already established during the optimistic early days of this forum covers the Essentials, but I would like to both formalize some additional guidelines and reiterate some of the most important existing rules, so that, should life return to these shores, this space can remain a pleasant and inviting place for pleasant and inviting humans.
First and foremost, a simple reminder. Bigotry of any kind is not tolerated. Period. And no, refusing to tolerate bigots is not a form of bigotry in its own right. We don't buy that line. We don't play that game. This includes dog-whistles, concern trolling, "just asking questions" about the validity of ethno-states or whether or not trans people should be allowed to use bathrooms, and so on. This hasn't been a major issue on here that I know of, but it always bears repeating, just in case.
Sir, This Is A Wandie's (sic) Drive Through
This is a tabletop roleplaying games community forum. The community part of the equation is, of course, important. Certain sub-forums are more appropriate for off-topic and topic-adjacent discussions, but I don't want to discourage anyone from bantering with buds and the like. Similarly, self promotion is totally acceptable on here, especially in the correct "channels." Anything that is too obviously spam and/or off-topic in a manner that clearly doesn't contribute to the local esprit de corps, however, will generally be deleted as soon as it is discovered.
Discourse is great. Many of us love a bit of discourse with our supper or breakfast. However, there is no one True and Correct way to design or play tabletop roleplaying games, so please try to refrain from language that may suggest otherwise. The only exception to this guideline is if the methods or practices being criticized are directly pertinent to and in violation of Rule One. For example, it's okay to criticize Big Name Elf Games for the ways in which they may perpetuate violent colonialist constructs, but you may want to avoid telling your fellow indies what they SHOULD do in their mechanical design practice, and instead try to focus on what works for you and your particular aims. Playtesting is not for everyone. Some people really like dice. Systems simultaneously matter and don't manner. I think we'll all have more fun if we intentionally cultivate a respect and a healthy curiosity for the methodologies of our fellow players, gms, and designers, so long as those methodologies aren't racist, sexist, transphobic, homophobic, etc.